What is the DOM and how is it structured?

TL;DR

The DOM, or Document Object Model, is a programming interface for web documents. It represents the page so that programs can change the document structure, style, and content. The DOM is structured as a tree of objects, where each node represents part of the document, such as elements, attributes, and text.

Definition

The Document Object Model (DOM) is a cross-platform and language-independent interface that treats an HTML, XHTML, or XML document as a tree structure. Each node in this tree represents a part of the document.

Structure

The DOM is structured as a hierarchical tree of nodes. Here are the main types of nodes:

Document node: The root of the document tree. It represents the entire document.
Element nodes: These represent HTML elements and form the bulk of the document tree.
Attribute nodes: These are associated with element nodes and represent the attributes of those elements.
Text nodes: These represent the text content within elements.
Comment nodes: These represent comments in the HTML.

Example

Consider the following HTML:

<!doctype html>
<html>
  <head>
    <title>Document</title>
  </head>
  <body>
    <h1>Hello, World!</h1>
    <p>This is a paragraph.</p>
  </body>
</html>

The DOM tree for this document would look like this:

Document
  └── html
      ├── head
      │   └── title
      │       └── "Document"
      └── body
          ├── h1
          │   └── "Hello, World!"
          └── p
              └── "This is a paragraph."

Accessing and manipulating the DOM

JavaScript can be used to access and manipulate the DOM. Here are some common methods:

document.getElementById(id): Selects an element by its ID.
document.querySelector(selector): Selects the first element that matches a CSS selector.
element.appendChild(node): Adds a new child node to an element.
element.removeChild(node): Removes a child node from an element.

Example:

// Select the <h1> element
const heading = document.querySelector('h1');

// Change its text content
heading.textContent = 'Hello, DOM!';

What is the DOM and how is it structured?

TL;DR